Allelochemicals, roots and competition

> From: Charley Bay <charleyb at hpgrla_gr.hp.com>
> Date: Fri, 22 Sep 95 9:35:39 MDT
> Subject: Re: Allelochemicals, roots and competition

> For the aquaria, we probably don't have our tanks up long enough
> witness an eco-typical shift over the maturation of the system
> (or the tank may not be large enough or not have the species 
> diversity adequate to allow a "natural" or otherwise competitive
> shift to take place). 

Actually I think I am witnessing this right now in my over-grown 
70G tank.  The front of this tank has been completely carpeted 
with Lillaeopsis. (which actually took over the space from E. 
tenellus during a prolonged heat wave summer before last)  I have 
had a stand of C. blassii in the end of this tank for some time.  
I am now seeing blassii babies popping up all through the 
Lillaeopsis.  Everywhere it happens, the Lillaeopsis retreats.  
Hwere it is the shade produced by the wide blassii leaves, root 
competition, or some other factor, I'm not sure.

> also
> many symbiotic relationships exist, such as mychoriyzae fungus
> aiding the water uptake to plant roots, or nitrosommonas bacteri
> fixing nitrogen in the root nodules of legumes, or mistletoe
> actually living in the vascular system of higher-order plants, o
> bromeliads relying upon shade, protection, and support [canopy
> positioning] from other plants).

Azolla holds a symbiotic nitrogen fixing cyanobacteria in its 
roots.  The Azolla gets to use the nitrogen captured by the 
cyanobacteria, and the Cyanobacteria has a safe sheltered home!

Karen Randall
Aquatic Gardeners Assoc.
Boston, MA